Music. According to the query of relevant information, the irregular rhythm group comes from "New Music Theory Tutorial". The author of "New Music Theory Tutorial" has been engaged in composition, conducting and music teaching for a long time. The knowledge in the book covers a wide range of knowledge and has a rigorous grasp of basic concepts. It uses practical content and Easy-to-understand language and detailed explanations, from easy to deep, tell students step by step how to identify various symbols in music and how to understand and master the basic knowledge of music.